Has anyone on here tried out for american idol before?

I am planning on driving down to Charleston, SC to try out for this
years american idol, I'm just wondering though if there are any tips
tricks or helpful hints as to what to do, what not to do and things of
that nature. What time should I get to try outs? What's the best way
to prepare my voice before hand? What kind of song should I do? Please
help! Thanks!